// Textbook fragment 05.12
  /** Test if stripped tag1 matches closing tag2 (first character is '/'). */
  public static boolean areMatchingTags(String tag1, String tag2) {
    return tag1.equals(tag2.substring(1)); // test against name after '/'
  }
  /** Test if every opening tag has a matching closing tag. */
  public static boolean isHTMLMatched(String[] tag) {
    Stack<String> S = new NodeStack<String>();  // Stack for matching tags
    for (int i = 0; (i < tag.length) && (tag[i] != null); i++) {
      if (isOpeningTag(tag[i]))
        S.push(tag[i]); // opening tag; push it on the stack
      else {
        if (S.isEmpty())
          return false;         // nothing to match
        if (!areMatchingTags(S.pop(), tag[i]))
          return false;         // wrong match
        }
      }
    if (S.isEmpty()) return true; // we matched everything
    return false; // we have some tags that never were matched
  }
  public final static int CAPACITY = 1000; // Tag array size
  /* Parse an HTML document into an array of html tags */
  public static String[] parseHTML(Scanner s) {
    String[] tag = new String[CAPACITY]; // our tag array (initially all null)
    int count = 0;                      // tag counter
    String token;                       // token returned by the scanner s
    while (s.hasNextLine()) {
      while ((token = s.findInLine("<[^>]*>")) != null)  // find the next tag
        tag[count++] = stripEnds(token); // strip the ends off this tag
      s.nextLine(); // go to the next line
    }
    return tag; // our array of (stripped) tags
  }
  public static void main(String[] args) throws IOException { // tester
    if (isHTMLMatched(parseHTML(new Scanner(System.in))))
      System.out.println("The input file is a matched HTML document.");
    else
      System.out.println("The input file is not a matched HTML document.");
  }
}